Global Navigation Satellite Systems (GNSS), such as a Global Positioning System (GPS), Global Navigation Satellite System (GLONASS), GALILEO and others are widely used for positioning, navigation and timing applications, due to the free availability of GNSS time.
Precise timing is crucial to a variety of activities, such as financial and banking networks, power stations and other crucial facilities, which all rely on precision timing for synchronization and operational efficiency, especially if they are located in different geographical facilities. Companies worldwide use GNSS timing to time-stamp business transactions, thereby providing a consistent and accurate way to maintain records and ensure their traceability. Banks use GPS timing to synchronize their network computers located around the world. Large and small businesses are turning to automated systems that can track, update, and manage multiple transactions made by a global network of customers. These applications require accurate timing information available through GNSS.
Also, distributed networks of instruments that must work together to precisely measure common events require timing sources that can guarantee accuracy at different locations. For example, integration of GPS time into seismic monitoring networks enables researchers to quickly locate the epicenters of earthquakes and other seismic events.
For example, telecommunication and computer networks require precise time synchronization to function properly. Cellular base stations must be synchronized with very high accuracy, in order to allow mobile devices to share limited radio spectrum more efficiently and to transfer the connection when transiting between stations. Mobile data networks use GPS timing as an accurate reference, in order to keep all the base stations synchronized. Digital broadcast radio services use GPS timing to ensure that the bits from all radio stations arrive to the receivers in precise timing. This allows listeners to toggle between stations with minimum of delay.
Electric Power companies and utilities use precise timing to allow efficient power transmission and distribution. Electric power substations use GPS-based time synchronization devices to improve time synchronization throughout the power grid in order to avoid power outages. By analyzing the precise timing of an electrical anomaly as it propagates through a grid, it is possible to trace back the exact location of any outage in the power line.
However, GNSS signals are vulnerable to in-band interferences because of being extremely weak broadcasted signals over wireless channels. Therefore, GNSS systems can be easily jammed, spoofed or blocked, intentionally or unintentionally without any alert, thereby posing a serious threat on the performance and on the functioning of systems which rely upon their timing. Even low-power interference is sufficient to easily jam or spoof GNSS receivers within a radius of several kilometers. Spoofing attacks are even more menacing than jamming since the target receiver is not aware of this threat. Commercial GPS is a backward compatible technology whose signal structure is in the public domain. This makes GPS technology more susceptible to disruptive interfering. Furthermore, recently the implementation of sophisticated spoofers has become more feasible, flexible, and less costly due to rapid advances in Software-Defined Radio (SDR) technology. Spoofing attacks are made using low-cost commercial equipment against a wide variety of GNSS receivers in which counterfeit GNSS signals are generated for the purpose of manipulating a target receiver's reported position and time. Such attacks threaten the integrity of financial transactions, communications, and power grid monitoring operations that depend on GPS signals for accurate positioning and timing.
Even though most of the spoofing attacks are directed to navigation applications, since the position data and timing are interrelated, most of the existing countermeasures can be used against timing spoofing or jamming, as well. One of the existing solutions for protecting timing applications is using a combination of a GNSS receiver and an accurate clock (e.g., a Rubidium Atomic Clock). Such a solution has been directed to mitigate the effects of GNSS signal loss, where the accurate clock is used as a backup (in case when the GPS signal is interrupted).
In some applications, internal modifications in an existing GNSS receiver of a system are complicated and intervention is the GNSS receiver's hardware is not desired.
Another problem arising from spoofing attacks is the generation of counterfeit position (or location) data, which overcome authentic position data and is received by GNSS receivers. Since the position data is massively used by vehicles, aircrafts, ships and numerous other applications, position data with compromised authenticity is highly dangerous and can cause to accidents or even lead aircrafts and ships to unwanted destinations.
It is therefore an object of the present invention to provide a securing apparatus for increasing the security and providing immunity of GNSS receivers against spoofing or jamming of timing and position data.
It is another object of the present invention to provide a securing apparatus for increasing the security and providing immunity against spoofing or jamming of timing, which does not require any modifications in the GNSS receiver.
Other objects and advantages of the invention will become apparent as the description proceeds.